Crystalline Crawler, Necklace of Girion, and Cloudstone Curio

Prerequisites

• Crystalline Crawler on the battlefield
• Necklace of Girion on the battlefield
• Cloudstone Curio on the battlefield
• available

Steps

1. Cast the creature that's castable for in your hand by paying its mana cost Necklace of Girion triggers, putting a +1/+1 counter on Crystalline Crawler
2. Resolve the creature spell
3. When the creature enters, Cloudstone Curio triggers, returning the other creature that's castable for from the battlefield to your hand
4. Activate Crystalline Crawler by removing a +1/+1 counter from it, adding
5. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite storm count